Malcolm in the middle

Aaron Paul auditioned for the role of Francis but lost. He would later be cast in 'Breaking Bad', which also starred Bryan Cranston.

On the show, Reese is the second oldest brother of Malcolm, but in real life, Justin Berfield (Reese) is less than three months younger than Frankie Muniz (Malcolm).

Cloris Leachman (Grandma Ida) and Kenneth Mars (Otto Mannkusser) both use the same German accents they used in 'Young Frankenstein'.